초록

In any database environment either wired or wireless, if multiple host access similar data items itmay lead to concurrent access anomalies. As disconnections and mobility are the commoncharacteristics in mobile environment, preserving consistency in presence of concurrent access is achallenging issue. Most of the approaches use locking mechanisms to achieve concurrency control.This leads to increase in blocking and abort rate in mobile environments. However the dynamic timeradjustment strategies may use locking mechanism to efficiently implement concurrency control. Toreduce deadlocks and blocking of resources an enhanced optimistic approach for concurrencycontrol is proposed. To show the effectiveness of the commit protocols in mobile environments, asimulator is designed and implemented to demonstrate how the transactions are committed and howthe data consistency is maintained when the transactions are executed concurrently. The simulatorwas tested for both pessimistic and optimistic approaches.